Accuracy Assessment of Sentinel-3 Satellite Altimetry in the Coastal Areas of the Azov Sea

Introduction. The Azov Sea is a shallow semi-enclosed sea where satellite altimetry (SA) faces challenges in ensuring accurate sea level measurements. This study focuses on verifying Sentinel-3 altimetry data in the coastal areas of the Azov Sea using observational platform data and a three-dimensional hydrodynamic model. Materials and Methods. The study is based on a comparison of sea surface heights (SSH) obtained from the Sentinel-3 radar altimeter with tide gauge data and modelling results. A three-dimensional hydrodynamic model, adapted to the conditions of the Azov Sea, was used, along with satellite data processed considering atmospheric and tidal corrections. Results. The root mean square error (RMSE) between satellite-derived and reference data was found to be 85 mm. The analysis demonstrated that Sentinel-3 Doppler altimetry in SAR mode provides higher accuracy compared to traditional altimetry, particularly in coastal areas. Discussion and Conclusion. The assessment of Sentinel-3 data confirms their reliability in modeling water levels in the Azov Sea. The comparative analysis methodology proposed in this study enables the identification of systematic errors in satellite data and facilitates their integration with modelling and in situ observations. The study confirms the effectiveness of Sentinel-3 data in determining sea levels in complex coastal conditions. The developed methodology can be applied to other coastal areas to assess satellite altimetry performance.